Wavelength-division-multiplexed (WDM) optical communications networks support multiplexed optical signals having many different spectral components or wavelengths. Each one of such wavelengths, referred to as a channel, represents an independent data stream. Before processing a WDM signal at any node within a network, it may be necessary to remove ("drop"), or, alternatively, to add, one or more spectral components to the WDM signal.
While WDM communications networks have been studied, theoretically, for years, there are few, if any, commercial implementations of such networks. Thus, while the need for a device capable of adding and/or dropping spectral components from a WDM signal has been recognized in the art, few if any of such devices have been described in the literature. It is clear, however, that regardless of its configuration, such a device should be transmission format independent, robust, fast and low cost.